Recent years have seen downsizing of camera modules. With this, the distance between lens and a solid-state imaging device is becoming smaller. As such, the angle of incident light, especially toward an outer perimeter of light-receiving region, causes deterioration in sensitivity characteristic and color mixture characteristic.
In view of the above, as a countermeasure for such deterioration in characteristics, a technique of forming a cavity or a low refractive index material between color filters has been presented as described in Patent Literatures (PTLs) 1, 2 and 3.
For example, FIG. 13 is a cross-sectional view showing a configuration of a conventional solid-state imaging device described in PTL 1. In the solid-state imaging device shown in FIG. 13, a hollow area 315 (having a refractive index of 1) is provided between adjacent color filters 309, and a cap layer 317 which seals the hollow area 315 is formed.
Furthermore, in the solid-state imaging device shown in FIG. 13 a photodiode 301 is formed in a silicon substrate. On the front surface side of the silicon substrate, multilayered wiring 306 is formed via an interlayer insulating film 305. In addition, on a surface of the upper most layer (corresponding to a lowermost layer in FIG. 13) of the multilayered wiring 306, a supporting substrate 310 is bonded via an adhesive layer 308. Furthermore, the photodiode 301 in the silicon substrate is isolated by an isolation region 319. In addition, on the back surface side of the silicon substrate, a color filter 309 is formed above the photodiode 301. The hollow area 315 is formed between the color filters 309.
The hollow area 315 is formed above the isolation region 319 by self-alignment. When oblique incident light enters each of pixels, most of the light reaching a side surface of the color filter 309 is reflected off because of the large difference between a refractive index of the color filter 309 and a refractive index of the hollow area 315, and light is collected onto the photodiode 301. Therefore, it is possible to improve the sensitivity characteristic and the color mixture characteristic.